1. Field of the Invention
This invention relates to an improved aramid paper which has high porosity while maintaining good tensile properties. The invention provides for adjustment of the porosity by compositional changes while yielding a paper with a smooth surface suitable for automatic processing where excessive surface roughness cannot be tolerated. The invention also relates to a process for making the improved high porosity paper.
This invention provides an improved aramid paper having good saturability and a smooth surface while retaining break strength.
2. Description of the Prior Art
U.S. Pat. Nos. 2,999,788 and 3,756,908, issued Sept. 12, 1961 and Sept. 4, 1973, respectively, describe nonwoven sheet structures utilizing aramid fibrids and aramid floc. Those patents describe the preparation of aramid fibrids and the use of such fibrids in making synthetic papers.
U.S. Pat. No. 3,920,428, issued Nov. 18, 1975, discloses preparation of filter media using a mixture of glass fibers and disintegrated synthetic papers of aramid fibrids and aramid floc. Glass fibers are required and only disintegrated paper is used.
British Patent No. 1,336,691, published Nov. 7, 1973, discloses nonwoven sheets utilizing aramid fibrids and floc of aramid or polyester.